Characterization of Transplant Center Decisions to Allocate Kidneys to Candidates With Lower Waiting List Priority

Key Points Question How often do kidney transplant centers skip candidates with the highest priority to place kidneys with recipients with lower-ranked allocation prioritization? Findings This cohort study of 26 579 organ offers from 3136 donors to 4668 recipients found that at 11 geographically isolated transplant centers, kidneys were placed further down the match-run than the candidate with the highest priority 68% of the time. Lower-quality kidneys were statistically significantly more likely to be placed with candidates further down the list than higher-quality kidneys. Meaning These findings suggest that transplant centers frequently skip over candidates to place kidneys with recipients with lower allocation priority, with limited oversight and transparency.

This supplemental material has been provided by the authors to give readers additional information about their work.

Data Cleaning
Using potential transplant recipient (PTR) match-run data from 2015-2019, we identified all match-runs local to the OPOs associated with OTO centers (n=5984). We excluded donors with zero kidneys placed locally (n=2545) or multiple match-runs generated (n=303), and dropped bypassed offers, offers past the final local acceptance, and offers to non-local candidates (e.g., rare, national 0-ABDR mismatch or high cPRA candidates that top the match-run). Gender and race/ethnicity were included as classified in the SRTR database. Data on donor characteristics were nearly complete (>98% complete for all variables). Missing or unknown values were combined into a "No/Unknown" category for the following donor variables: donor history of diabetes (n = 15, 0.32% unknown), donor history of hypertension (n = 27, 0.58% missing), donor proteinuria (n = 37, 0.79% unknown), donor history of cancer (n = 19, 0.41% unknown), donor history of smoking (n = 85, 1.8% unknown). For missing continuous values, complete case analysis was performed with the excluded missing values noted in the table footnotes: donor creatinine (n = 2, 0.04% missing). For recipient data, all variables were >99% complete and complete case analysis was performed with the exclusions of missing values noted in the table footnotes. Preemptive listing was defined as no dialysis start date reported or a dialysis start date later than the initial listing date.

EPTS Comparisons
For each declined offer, we calculated the difference in Estimated Post-Transplant Survival (EPTS) score between the skipped candidate and the ultimate recipient of the kidney. If both donor kidneys were transplanted, although the skipped candidates would appear only once in the match-run, they were compared against the recipient of any kidney they were eligible to receive. For example, if the kidneys were accepted for the candidates at match sequence positions 2 and 4, the skipped candidate ranked at number 1 would be compared to both recipients at 2 and 4, and the skipped candidate ranked at number 3 would be compared to the recipient at 4 only.

Sensitivity Analyses
Significant changes to the Kidney Allocation System were implemented in March 2021 that eliminated local Donation Service Area (DSA) boundaries and incorporated distance from the donor hospital in the allocation prioritization algorithm in an effort to improve geographic equity in kidney transplantation. Under this new distance-based allocation system (referred to as "KAS-250"), the 11 transplant centers included in our study that had previously experienced a one-to-one relationship with their Organ Procurement Organization (OPO) would now be more likely to have additional candidates listed at other transplant centers appearing in the match runs for the local donors recovered by their OPO. As a result, if the transplant center did not accept the organ offer for their highest-ranked candidate, they now had a greater chance of losing that kidney to a candidate at another center before it could be allocated to the next-ranked candidate at their own center. To examine whether the observed patterns in kidney placement at these centers held under a new allocation system with more competition from other transplant centers, we repeated our primary analysis using the data that was available from the first 9 months of the new allocation system (3/16/2021-12/31/2021).
To help contextualize the findings at these 11 centers, we also examined kidney placement patterns at all 231 transplant centers receiving any deceased donor kidney offers in 2019. We calculated how frequently transplant centers placed kidneys from their local donor match runs with their highestranked candidate versus a lower-ranked candidate at their center, both overall and by individual center.